Handrails and stairs are everyday objects normally taken for granted. Absent or inappropriate handrails and poorly designed stairs cause or contribute to thousands of accidents every year. In the United States it has been estimated that 998,871 people received hospital treatment for injuries that occurred on stairs during 1990. In 1976, approximately 4,000 people were estimated to have died as a result of falls on stairs. These statistics indicate that stairs are a dangerous as building fires, however, these accidents receive much less attention and research. Various authors have noted a higher incidence of falls on stairs without handrails. In the general population, studies have attributed approximately 15% of stair accidents to missing handrails. The injuries that result from absent or inadequate handrails range from simple sprains to falls resulting in death. Handrails perform the following functions:
Aid in the maintenance of balance while ascending or descending.
Provide emergency support to regain balance if it has been lost.
Aid those with mobility difficulties in ascending stairs.
Provide directional guidance for the visibly impaired.
The use of a handrail provides an opportunity to avoid or lessen the severity of an accident. It does not guarantee that an accident will not occur. Often the forces related to the fall are greater than the ability to maintain a grip on the handrail. Of course, if the handrail is not being used, it is less likely to be helpful since the victim must be able to quickly reach it and apply a strong grip. This is easier for young persons but is also a function of the handrail design. The stair should be laid out so that stair users choose a path close to the handrail, making use more likely and allowing it to be grasped in an emergency. The handrail itself should be a shape that allows a strong grasp to be applied. The handrail material should not be slippery to maximize friction forces. The position of the handrail at a convenient height and distance from the walls is important. The transmission of forces between the handrail and hand has two components, one perpendicular and one tangential to the handrail. The tangential force is caused by friction between the handrail and the hand. The frictional force varies with the handrail normal forces which are maximized by the "power grip" illustrated in the figure. The wrap around power grip brings all of the hand and the finger segments into contact with the handrail generating the maximum possible effective normal forces. The power grip also increases the contact area between the hand and handrail reducing the stress on the hand.
Handrails have been a requirement in Canadian Building Codes for many years. However, we often encounter accidents that have occurred on stairwells where no handrail was provided.
Since 1986, the Ontario Building Code has provided a recommended maximum size for handrails. The relatively small diameter handrail that is now considered appropriate design maximizes the strength of the grip that can be made on the handrail, thus maximizing the chance for recovering after a loss-of-balance. The recommended design is based upon studies comparing the strengths obtained with different handrail shapes. Wide handrails and deep handrails were found to cause low grip strength relative to the recommended design.
Recent court cases have held that wide handrails do not meet current standards for safe premises under the Occupiers Liability Act. The absence of the handrail or the presence of an inadequate handrail is easily documented with a site visit and illustrated with photographs and drawings comparing the inadequate handrail to a design that maximized grip strength.
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Walters Forensic Engineering | 277 Wellington
Street West, Suite 800 | Toronto, ON M5V 3H2